The United States declared its independence on July 4, 1776, but that didn’t make it a nation. Sheets of paper, even ones on which well-intended men pledge their “lives, fortunes and sacred honor” to abandon one government for a new government, don’t create nations. Nations cannot be simply declared to exist. They emerge slowly from the shared experiences, good and bad, of generations.

The United States wouldn’t become a nation for nearly another 100 years, after other, equally well-intended men pledged their own lives, fortunes and sacred honor to abandon one government for a new government. The important distinction, of course, is that these men pitted themselves against what were until recently their fellow Americans, enemies now in a great civil war that would claim almost as many American lives as every other U.S. conflict combined and, by war’s twisted logic, forge the nation the Founding Fathers could not.

The Civil War shaped America’s national character in unforeseeable ways. That a world-dominant power should rise in North America was a consequence of advantageous geography. That the power that came to be was this particular United States of America was not predetermined. Power is predictable in a way that national character is not. The rise of the U.S. was predictable. The birth of an American nation at Gettysburg was not.

The Abdication of Duty

To understand how this was possible, we must begin with the Civil War. It was not a war the South could win by dint of arms alone. The North had more soldiers, more (and better) weapons, and more industrial capacity. The South’s only chance at victory was to protract the conflict long enough to break the Union’s will, forcing Washington to negotiate the South’s freedom with slavery intact.

In May 1863, the situation looked grim for the Confederacy. Gen. Ulysses S. Grant laid siege to the city of Vicksburg, his victory inevitable. Union control of Vicksburg would cut the fledgling Confederacy in half and put the full length of the Mississippi River in the hands of the North. The Confederacy had one hope left: the Army of Northern Virginia, which had time and again defeated, even humiliated, the Army of the Potomac. It was commanded by Gen. Robert E. Lee.

Lee decided that his army, having been properly reinforced, should be deployed offensively into Union territory. He had tried to do so once before in 1862, only to be turned back at the Battle of Antietam/Sharpsburg. Lee believed he failed only because the Union commander, Gen. George McClellan, had intercepted his marching orders. Lee regained his composure, and the general disrepair of the Union command structure only boosted his confidence.

Strategy as much as vanity informed his foray into the North. Lee could not have convinced the president of the Confederacy or his secretary of war to support the plan had it not made strategic sense. Lee knew he couldn’t defend Virginia forever; his army was sustaining far too many casualties. The Confederacy needed something more if it had any chance of peace on its terms. And since provisions for the Confederate army were running low, it needed something quick. Most important, however, was the state of affairs at Vicksburg. Lee could not rescue Vicksburg any more than he could draw Grant away from a foregone victory. The only option he had was to overshadow the Union victory at Vicksburg with an even greater victory of his own.

His was a desperate strategy, but it could have turned the tide of the war if it had succeeded. Defeating the Union on its own ground would bring to the Confederacy much needed international prestige, recognition from Great Britain or even intervention from France. It would crush the morale of the Union and, in turn, the faith it had in Abraham Lincoln, who stood for re-election but would not stand for ending hostilities with the South. Moving the Army of Northern Virginia into Pennsylvania was a bold move, but he had no other choice. Fortune does not favor the bold – misfortune and weakness make the bold necessary.

And so for a second time Lee led his army north, and, for a second time, plans went awry. It is under these circumstances that Union and Confederate soldiers met for three days, beginning on July 1, 1863, at Gettysburg, fighting and dying in what would become the Civil War’s most important battle. The Confederacy had to fight – and it had to win – if it were to survive. Gettysburg would decide the fate of the project started on July 4, 1776.

The men who fought at Gettysburg were brought there by forces they could not control. The U.S. Constitution, ratified in 1788, had only papered over the inherent North-South divide of the original 13 colonies. Now, industrialization threatened the Southern way of life, and secession threatened the Northern. But while the war itself was inexorable, the Battle of Gettysburg was not predetermined. Its result was decided by a single mistake, made by the most brilliant military mind in the war: Lee’s. Had Lee made a different choice, the United States might have been a much different nation. It was a rare moment in history in which the forces that ordinarily shape human civilization abdicate their duties, leaving the work instead to the mortals over whom they otherwise have domain.

The Possible and the Impossible

Lee’s fatal mistake, of course, was the ordering of Pickett’s Charge. On the third day of battle, Lee ordered 15,000 men to march just under a mile, with scarcely any cover, to assault a heavily armed and well-defended Union position along Cemetery Ridge. Hardly any men made it to their destination. One-third of the Confederate soldiers were either killed or captured. The overall casualty rate was more than 50 percent – among officers, that rate was more than 80 percent. Lee ordered the charge despite all the evidence that it would fail.

So why did Lee, intelligent as he was, order the charge? For students of history, this question is as impossible to answer as it is to ignore.

We can rationalize the decision, but only to a degree. The battle began July 1, earlier than Lee meant for it to, at a venue he did not choose. Under his orders, the battle would not commence until the full Confederate force had mustered. But Confederate soldiers encountered and then engaged Union soldiers – soldiers they had not known were there – in the town of Gettysburg.

The Confederates hadn’t known because Lee himself was in the dark. He had been deprived of the use of his cavalry, commanded by Maj. Gen. Jeb Stuart, the person on whom Lee depended for intelligence. Stuart had lost touch with Lee around June 25 while the cavalry was on a raid. Stuart, hoping to make amends for being caught off guard by Union forces earlier in the month, had ridden around the Army of the Potomac to attack a Union supply chain. Stuart’s raid was successful, but it also put the Army of the Potomac between Stuart and the rest of his army. By the time Stuart returned, the Battle of Gettysburg had already begun. Stuart’s tardiness doesn’t explain Pickett’s Charge, of course, but it helps to explain why Lee gave up on one of the most important parts of his invasion plan: choosing the field of battle on his terms.

And yet the Confederates still nearly won – a fact often cited for influencing Pickett’s Charge. The first day of fighting was marked not by Union superiority but by a Confederate mistake. Dick Ewell, the new commander of the Army of Northern Virginia’s reorganized Second Corps, had beaten the Union forces he faced near Culp’s Hill. He had the numbers, not to mention the strategic reason, to take the hill, yet he delayed his assault because in his inexperience, he misinterpreted Lee’s orders. Had he not delayed it, Gettysburg might have been a small skirmish on the way to a bigger battle somewhere else, presumably a battlefield of Lee’s choosing.

Victory was within reach for the Confederacy on the second day too, despite the Union’s formidable defensive position. Gen. James Longstreet, Lee’s most trusted and experienced commander, had counseled Lee to leave Gettysburg after the first day of the battle and to instead position their forces between Washington and the Union army, forcing the Union to take the offensive. But several things militated against their departure. Lee had only limited intelligence on the disposition of the Union’s forces, and in any case, he didn’t believe he could attempt such a maneuver without his cavalry, which would not rejoin the main force for another 24 hours. Furthermore, he had almost won on the first day. His troops were amply supplied. And the Union army, operating under the new leadership of Gen. George Meade, was unsure of itself. In fact, it wasn’t even at full strength. Lee decided, not unreasonably, that the fight would continue in southern Pennsylvania.

And it was nearly the right decision. Even Longstreet, who had been skeptical of the July 2 attack, wrote in a private letter that he had let the offensive go on longer than it should have because of how successful his troops had been. Had it not been for last-minute heroics by Union Cols. Patrick O’Rourke and Joshua Lawrence Chamberlain, Longstreet’s forces might well have seized the strategic high ground of Little Round Top. At one point, Confederate troops even managed to open a gap in the Union lines at Cemetery Ridge but could not afford to punch through it with the numbers they had. From where Lee sat on the battlefield, the Confederates had nearly won. The only thing his army lacked was what he called “proper concert of action.”

Maybe this explains why Lee was tempted to push forward, against the advice of his confidants – Longstreet and Ewell counseled restraint – and against all available evidence that suggested Pickett’s Charge would fail. But it doesn’t explain why he ordered what amounted to a suicide mission. It doesn’t explain why Lee failed to notice his depleted artillery stores – the munitions that would have supported the assault. (What artillery Lee did have ended up shooting too high, doing little to soften the Union’s defenses.) It doesn’t explain the ambiguity of his orders the night before the attack, nor why Ewell began the assault well before Maj. Gen. George Pickett was in position. It doesn’t explain why Lee deployed Stuart’s recently returned but completely exhausted cavalry to attack the Union’s rear instead of sending it to gather better intelligence. (He might have learned that Union reinforcements had arrived.) And it doesn’t explain why Lee, who was smart enough to know that things were going south, didn’t call off the attack.

Ultimately, there is only one explanation for Lee’s actions, and for those of us who believe, as Hegel does, that “to him who looks upon the world rationally, the world in its turn presents a rational aspect,” it’s not a very satisfying answer. Lee was simply blinded by his passions. He saw what he wanted to see, not what was really in front of him, and no amount of intelligence would have changed his mind. Lee was exhilarated because he was in enemy territory. He knew that the future of Virginia – his nation – depended on the invasion’s success. He disrespected Union troops as much as he admired his own. They had come so far and had come so close to victory, and he believed they would not be deterred. In the end, they were not deterred. They were defeated.

A memorial stands at Cemetery Ridge. TIM SLOAN/AFP/Getty Images

If we accept that Pickett’s Charge was unreasonable, then the question is not why Lee did what he did but why a general as skilled and disciplined as Lee would indulge in self-delusion at the most important juncture of his military career. The simple answer is that Lee was human, and humans make mistakes. But the Confederacy couldn’t afford to make the kinds of mistakes Lee made at Gettysburg if it hoped to win the Civil War. With such a small margin of error, the South, short of perfection, was always going to lose. And even perfection might not have been enough to overcome the odds.

Predicting history is easy, of course. To say the South wouldn’t win is to state the obvious. Historical counterfactuals are just as easy in that they’re impossible to disprove and nearly impervious to intellectual rigor. Still, on July 3, 2017, the day before the United States’ 241st birthday, it’s useful to stop and consider that a single man’s mistake in 1863 played a significant role in defining a nation that would become the most powerful the world had ever seen.

We are travelers on a cosmic journey, stardust, swirling and dancing in the eddies and whirlpools of infinity. Life is eternal. We have stopped for a moment to encounter each other, to meet, to love, to share.This is a precious moment. It is a little parenthesis in eternity.